The present invention relates to a pickup cartridge of a movable magnet type, which can draw right and left channel signals separated independently from the modulation grooves of a record.
Generally, as a pickup cartridge of a movable magnet type, it is known that four pole pieces are arranged in a square shape to make a common gap, and a rod-shaped magnet provided at the other end of a cantilever with a needle point at its tip end is caused to be oscillated within the common gap to draw the right and left channel signals separated from the modulation grooves of the record. However, in the pickup cartridge of movable magnet type using such rod-shaped magnet of conventional, a magnet having a magnetic axis parallel to the axial direction of a cantilever is required to be used as a rod-shaped magnet and the central portion thereof is required to be supported for free angular motion. In addition, to cause the sufficient power generation, the rod-shaped magnet itself is required to be considerably made longer in the axial direction of the cantilever. Thus, the effective mass of the vibration system including the rod-shaped magnet becomes considerably larger, thus resulting in decreasing of the sensitivity thereof.
In order to solve a problem of the sensitivity decrease of the movable magnet type pickup cartridge using such rod-shaped magnet, it is proposed that a magnet holder is provided at the other end of the cantilever and two rod-shaped magnets are disposed on the magnet holder so that they may become orthogonal to the maximum sensitivity axis of the modulation groove of a 45.degree.-45.degree. system stereo record. However, in the pickup cartridge of a movable magnet type wherein two rod-shaped magnets are disposed, being orthogonal to the maximum sensitivity axis of the modulation groove of the 45.degree.-45.degree. system stereo record, two rod-shaped magnets are used, which have magnetic axis parallel to the maximum sensitivity axis of the modulation groove, so that the opposed portion of the movable magnet is necessarily caused in the different polarity or the same polarity. Thus, with the above construction of pickup cartridge, the magnetic flux distribution is deformed and is unbalanced around the maximum sensitivity axis and, accordingly, the modulation axis changes, resulting in various problems such as varied output, deteriorated separation or the like.